In 5GS (e.g. 3GPP TS 33.501), it is required for UEs to send Subscription Concealed Identifier (SUCI) that was encrypted from Subscription Permanent Identifier (SUPI) to the 3GPP network. The UE performs the encryption of SUPI with Public Key identity configured by the HPLMN and protection scheme. The encrypted identity is called Subscription Concealed Identity (SUCI). The SUCI is sent to the AMF in a Non Access Stratum message (e.g. Registration Request or Identity Request message). On receiving the SUCI, the AMF sends a message including SUCI to the AUSF and AUSF sends SUCI to UDM. The UDM de-conceals the SUCI to SUPI and sends it to AUSF and AUSF returns it to the AMF. The AMF now knows the SUPI of the user and performs the corresponding NAS procedure. SUCI is one time identifier.